AC Size Calculator
A quick rule-of-thumb estimate of air conditioner size from square footage, climate and ceiling height. Use it for ballpark quotes; size the final system with a Manual J load calculation.
How AC sizing works
One ton of cooling equals 12,000 BTU per hour. A common rule of thumb is about 20 to 30 BTU per square foot depending on climate, adjusted up for ceilings taller than 8 feet. Residential systems come in half-ton steps from 1.5 to 5 tons.
This is only a starting point. Insulation, windows, sun exposure, duct design and the number of occupants all matter. Oversized units short-cycle and leave humidity behind, so confirm with a Manual J load calculation before installing.
Questions
What size AC do I need for 2,000 square feet?
Roughly 4 to 5 tons in a mixed or hot climate by rule of thumb. A Manual J calculation gives the right answer for the specific home.
How many square feet does a ton of AC cool?
Typically about 400 to 600 sq ft per ton, depending on climate and insulation.
Is a bigger AC unit better?
No. An oversized unit cycles on and off too often, removes less humidity and wears out faster.